What is the approach to a patient with altered mental status, considering their demographic information, past medical history, and potential underlying conditions?

Approach to Altered Mental Status

Immediate Stabilization

Begin with airway assessment and vital signs, transferring patients with Glasgow Coma Scale <8 or Grade 3-4 altered mental status to ICU-level monitoring immediately. 1

• Intubate for inability to maintain airway, massive GI bleeding, or respiratory distress 1
• Use short-acting sedatives (propofol or dexmedetomidine) instead of benzodiazepines to preserve cognitive function and reduce ventilation duration 1
• Document vital signs immediately, as fever suggests infection, hypotension suggests shock, and hypertensive emergency requires urgent intervention 2, 3

History and Physical Examination

History and physical examination have 94% sensitivity for identifying medical conditions—far superior to laboratory testing alone (20% sensitivity)—making thorough clinical assessment the cornerstone of evaluation. 4, 1, 2

Critical History Elements to Obtain:

• Medication review including all prescriptions, over-the-counter drugs, and supplements (bring in bottles if possible) 4
• Substance use history including alcohol, illicit drugs, and recent withdrawal 4, 2
• Timeline and fluctuation pattern (delirium fluctuates throughout the day with lucid intervals) 3
• Baseline cognitive function and any prior psychiatric history 4
• Recent infections, trauma, or falls 2

Physical Examination Priorities:

• Assess for focal neurological deficits (significantly increases likelihood of intracranial pathology requiring immediate neuroimaging) 2
• Evaluate for signs of trauma, toxidromes, and infection sources 2
• Check for anticholinergic signs, meningismus, and asterixis 4, 1
• Quantify mental status objectively using Glasgow Coma Scale or West Haven criteria 2

Laboratory Workup

Obtain comprehensive metabolic panel including complete blood count, electrolytes, glucose, renal function, liver function tests, and urinalysis in all patients. 1, 2

• Perform toxicology screens and obtain drug/alcohol levels based on history 1, 2
• Do NOT routinely measure ammonia levels for diagnosis of hepatic encephalopathy, as they are variable and unreliable 1, 2, 3
• In elderly patients, obtain chest X-ray, ECG, BUN, and serum B12 4
• Only 1.4% of laboratory tests lead to diagnosis of conditions not already detected by history and physical examination 4

Neuroimaging Decision Algorithm

Obtain head CT without contrast immediately if any of the following are present: 4, 1, 2, 3

• First episode of altered mental status
• Focal neurological deficits or new focal neurological signs
• Seizures
• Increased intracranial bleeding risk (anticoagulation, thrombocytopenia)
• Hypertensive emergency
• History of trauma or falls
• History of malignancy
• Headache with nausea or vomiting

Brain MRI may be appropriate when CT is negative but clinical suspicion remains high, or when inflammatory conditions, encephalitis, or subtle vascular pathologies are suspected. 2

Do NOT routinely obtain neuroimaging in clinically stable psychiatric patients who are alert, cooperative, with normal vitals and noncontributory history/physical examination. 1, 2

Systematic Etiologic Investigation

Most Common Causes by Prevalence:

1. Neurological (30-35%): intracranial mass, stroke, encephalitis, meningitis 1, 2
2. Toxicologic/Pharmacologic (20-25%): medication side effects, alcohol intoxication/withdrawal, illicit drugs 1, 2
3. Metabolic/Systemic (15-20%): hypoglycemia, hyperglycemia, electrolyte abnormalities, hepatic encephalopathy, uremia 1, 2
4. Infectious (9-18%): sepsis, urinary tract infection, pneumonia, meningitis 1, 2

Special Considerations for Cirrhotic Patients:

In cirrhotic patients, hepatic encephalopathy is a diagnosis of exclusion—always investigate alternative causes including alcohol intoxication, infections, and electrolyte disorders. 1, 3

• Do not rely on ammonia levels alone; a low ammonia level should prompt investigation of other etiologies 3
• Approximately 90% of patients improve with correction of the precipitating factor alone 1, 2

Delirium Recognition:

Delirium is the most common presentation in elderly patients (10-31% at admission, up to 56% during hospitalization) and carries twice the mortality if missed. 3, 5

• Cardinal feature is inattention with fluctuating course throughout the day with lucid intervals 3
• ED physicians miss delirium in more than 50% of cases 5
• Always consider multiple concurrent etiologies, especially in elderly patients where delirium is often multifactorial 1, 2, 3

Empiric Treatment While Awaiting Results

Do not delay empiric treatment while awaiting diagnostic results in potentially life-threatening conditions. 2, 3

• Start intravenous acyclovir 10 mg/kg three times daily immediately in suspected encephalitis, especially in immunocompromised patients 2
• For suspected hepatic encephalopathy, initiate lactulose or polyethylene glycol, and consider rifaximin as add-on therapy 1
• Avoid or minimize opioids, benzodiazepines, and gabapentin due to synergistic sedating effects 1

Critical Pitfalls to Avoid

Never attribute altered mental status solely to psychiatric causes without completing a full medical workup—this is the most dangerous error. 1, 2, 3

• Do not skip thorough clinical assessment despite availability of advanced testing 4, 1
• Do not rely on ammonia levels alone to diagnose hepatic encephalopathy in cirrhotic patients 1, 2, 3
• Always consider multiple concurrent etiologies, especially in elderly patients 1, 2, 3
• Do not delay empiric treatment for life-threatening conditions while awaiting diagnostic results 2, 3
• Remember that mortality doubles if delirium diagnosis is missed 1, 3

Patient and Environmental Factors in Dementia Patients

For patients with underlying dementia presenting with behavioral changes:

• Investigate undiagnosed medical conditions including pain, urinary tract infection, constipation, dehydration, and anemia (disproportionately more common than in those without cognitive impairment) 4
• Assess medication profile for anticholinergic properties and drug interactions 4
• Evaluate caregiver understanding and communication styles, as caregivers may believe the patient is "doing this on purpose" 4
• Consider environmental factors including over/under-stimulation, lack of predictable routines, and home safety 4